Padlocks are frequently used to prevent opening of various types of locks such as bolt locks, hasp locks and double angle locks. Generally speaking, the padlock is easily accessible to tampering. The padlock may be broken by using bolt cutters he shackle away from the body of the padlock. Various arrangements have been proposed to protect padlocks from this form of tampering. See for instance U.S. Pat. Nos. 4,033,156; 4,238,941; 3,828,591; 4,879,889; and 3,718,014; U.K. patent specification Nos. 2,206,376A and 2,185,519A; and Australian patent specification Nos. 26903/88; 23818/88; 60776/86; 57622/80; 66735/90 and 38235/89. Another weakness with locks which are secured by padlocks is the problem of sawing through the shackle, loop or hole through which the padlock shackle passes so as to open the lock. This problem is addressed by some of the known arrangements but they tend to be cumbersome or involve providing a substantially closed housing for the padlock. U.K. specification No. 2,185,519A discloses a comparatively simple device but it would have the practical disadvantage that the lock to which it is coupled would not be satisfactorily protected. Also it appears to be restricted to use with only hasp and staple types of locks.